A 3 years and 3 months old, intact male domestic cat was presented with multiple papules and nodules as well as generalized sclerema. Histopathological analysis of the tissue samples obtained by skin biopsy and necropsy revealed an extensive and aggressive proliferation of spindle cells not only in sclerematous skin and the cutaneous nodules, but in skeletal muscle membranes and serosa. The findings in some cutaneous nodules were consistent with those of fibrosarcoma. Immunohistochemical analysis with anti-feline leukemia virus revealed cytoplasmic staining of those proliferating spindle cells, suggesting that the histopathological changes were associated with feline leukemia virus or feline sarcoma virus.

We report a case of subcorneal pustular dermatosis in a dog with characteristic clinical symptoms and histopathological findings. Papule and pustule formations were observed throughout the body. Aseptic pustular dermatosis was diagnosed based on bacterial culture tests. A histopathological examination revealed subcorneal pustule formation. The dog had flea bites and heat stroke before the development of pustules; furthermore, no pustules were found during or immediately after administering the treatment specific to these conditions. This confirms that the lesions we observed were in the early stages of their development. Previous case reports have indicated that the early stages of this condition are not necessarily accompanied by itching. The patient’s condition improved rapidly after treatment with dapsone.